Notwithstanding the increasing sophistication of military aircraft, there is a trend toward increasingly austere basing requirements for such aircraft. It is supposed that forward bases established in recently acquired or potentially hostile territory will quite likely be devoid of the sophisticated ground support equipment that is necessary for the support of the increasingly sophisticated on board aircraft systems.
Conventionally, such systems include the provision of an inert gas such as so-called nitrogen enriched air (NEA) for use in inerting fuel tanks. As fuel is consumed in a fuel tank, the voided volume is filled with NEA to displace any oxidant that might combust with fuel vapor within the tank as a result of the plane being struck during combat or the like. Such systems also provide oxygen for crew life support.
One system that has been proposed to provide gases for the functions mentioned immediately preceding is illustrated in U.S. Pat. No. 4,681,602 issued July 21, 1987 to Glenn et al.
At the same time, there are other needs for oxygen and inert gas on aircraft and replenishment stores are not considered to be readily available at forward bases, nor are the means required to produce the requisite gases for replenishment of aircraft installed NEA or oxygen consuming units easily obtained. Consequently, distinct on board systems to meet these needs have been proposed.
These various operationally distinct systems have several disadvantages because of the number of differing systems attempting to perform similar functions, dissimilarity of the same, and complexity. Maintenance and spare costs are also high. Furthermore, the additional logistic costs associated with system consumables and ground support equipment for each distinct system enhances the problem.
In some systems, such as one wherein the use of hydrazine is employed to provide a means for rapidly starting an emergency power unit, the safety hazard that arises from handling such materials is undesirable. The independence of the various systems on board the aircraft also imposes a weight and volume penalty and because the aircraft is heavily dependent on ground support as a result, turnaround time between operations is higher, the flexibility to base the aircraft where desired is lower, and the vulnerability of the aircraft at ground attack is increased.
The present invention seeks to overcome one or more of the above problems.